Field of Invention
This application relates to traffic intersections at grade specifically to an arrangement of lanes, detectors and traffic signal means.
Background of the Invention
Conventional traffic intersections with signal control have different movements of traffic (left turn, through and right turn) on the same approach all stop parallelly or side by side at the intersection at a red light until the traffic movements receive their turn of green light. A high volume of left turn traffic requires a long left turn signal phase and even warrants multiple dedicated turn lanes. Long left turn phases increase travel delay and more turn lanes create a wider intersection. A wider intersection will increase pedestrian crossing time and crossing distance through the intersection thus reducing pedestrian safety. A wider intersection also requires longer signal phasing clearance times (all red interval), and a longer pedestrian crossing time requires longer signal phase associated with the crossing. These will reduce intersection operational efficiency. Furthermore, right of way is not always available for widening the intersection.
Since all traffic stops and queues at the intersection for red light, when the green light starts, there is a startup delay due to driver's perception, reaction, and vehicle acceleration process. The startup delay is typically distributed to the first few queued vehicles. Also some drivers in the queue are not attentive to the signal change to green. The time headway between their vehicles and the preceding vehicles could be extra-large due to their late reaction.
When yellow light initiates at a conventional intersection, some through traffic drivers at a certain distance away from the intersection may have difficulty deciding whether to go or prepare to stop, and some through traffic drivers have a tendency to speed up to beat the upcoming red light. Severe accidents could happen if they did not make it.